An oil control ring according the present disclosure includes a pair of side rails, and a spacer expander disposed between the pair of side rails. The spacer expander includes a plurality of sets and each set includes a lug part and a rail facing part. For each set, the lug part is in contact with an inner circumferential surface of either of the pair of the side rails, and the rail facing part is provided adjacent to the lug part and faces a side surface of either of the pair of the side rails. The lug part satisfies a following condition (1):
W/H≥1.5  (1)
In condition (1), W indicates a width of the lug part at a position 0.05 mm away from a highest position of the lug part in a direction towards the rail facing part, and H indicates a height difference between a highest position of a region on the rail facing part adjacent to the lug part and the highest position of the lug part.

A multi-piece piston ring includes an upper scraper ring 10 comprising two flank surfaces, an outer scraping surface/edge, and an inner spring contact surface. A lower support ring 4 includes two flank surfaces, an outer spring contact surface, and a support ring inner surface. An expander spring/spiral spring 8, which, on an upper and lower side, is operational to abut against a respective lower flank surface of the upper scraper ring 10 and against the upper flank surface of the support ring 4. Scraper ring contact projections protruding upwards on an inner spring side, and support ring contact projections protruding downwards on an outer spring side, wherein the scraper ring contact projections are to each abut against the inner spring contact surface of the scraper ring 10, and support ring contact projections protruding downwards are to abut against the outer spring contact surface.

A multi-piece piston ring includes an upper scraper ring 10 comprising two flank surfaces, an outer scraping surface/edge, and an inner spring contact surface. A lower support ring 4 includes two flank surfaces, an outer spring contact surface, and a support ring inner surface. An expander spring/spiral spring 8, which, on an upper and lower side, is operational to abut against a respective lower flank surface of the upper scraper ring 10 and against the upper flank surface of the support ring 4. Scraper ring contact projections protruding upwards on an inner spring side, and support ring contact projections protruding downwards on an outer spring side, wherein the scraper ring contact projections are to each abut against the inner spring contact surface of the scraper ring 10, and support ring contact projections protruding downwards are to abut against the outer spring contact surface.

An oil control ring according the present disclosure includes a pair of side rails, and a spacer expander disposed between the pair of side rails. The spacer expander includes a plurality of sets and each set includes a lug part and a rail facing part. For each set, the lug part is in contact with an inner circumferential surface of either of the pair of the side rails, and the rail facing part is provided adjacent to the lug part and faces a side surface of either of the pair of the side rails. The lug part satisfies a following condition (1):

W/H≥1.5   (1)

In condition (1), W indicates a width of the lug part at a position 0.05 mm away from a highest position of the lug part in a direction towards the rail facing part, and H indicates a height difference between a highest position of a region on the rail facing part adjacent to the lug part and the highest position of the lug part.

In a combination oil ring, when a line passing through a center of a segment width is a first intermediate line, a length of a line segment between a position on an engine combustion chamber side and a position on a side distant from the engine combustion chamber on a contour curve at a position at a distance of 3 m from an outer peripheral vertex toward an inner peripheral side in a segment radial direction is L, and an intermediate line of the line segment L is a second intermediate line, the second intermediate line is located on the side more distant from the engine combustion chamber than the first intermediate line, and the outer periphery vertex of the segment is located on the second intermediate line or on the side more distant from the engine combustion chamber than the second intermediate line.

In a combination oil ring, when a line passing through a center of a segment width is a first intermediate line, a length of a line segment between a position on an engine combustion chamber side and a position on a side distant from the engine combustion chamber on a contour curve at a position at a distance of 3 m from an outer peripheral vertex toward an inner peripheral side in a segment radial direction is L, and an intermediate line of the line segment L is a second intermediate line, the second intermediate line is located on the side more distant from the engine combustion chamber than the first intermediate line, and the outer periphery vertex of the segment is located on the second intermediate line or on the side more distant from the engine combustion chamber than the second intermediate line.